Background Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease globally, with its prevalence rising worldwide. This study aimed to evaluate the knowledge, attitudes, and determinants related to NAFLD among adults in Jazan, Saudi Arabia. Methods A cross-sectional study was conducted using a validated online questionnaire distributed to 540 participants in Jazan Province. Data analysis involved descriptive and comparative statistics to assess knowledge, attitudes, and influencing factors related to NAFLD. Results The majority of participants (244, 45.2%) demonstrated poor knowledge about NAFLD, while 226 (41.9%) had fair knowledge. Notably, individuals aged 40-49, males, healthcare workers, those with obesity and diabetes mellitus, and those with a family history of NAFLD showed significantly higher levels of knowledge (p < 0.05). Regarding attitudes, most participants (64.4%) exhibited a positive attitude toward NAFLD, 28.3% had a satisfactory attitude, and only 7% demonstrated a poor attitude. Conclusion The findings highlight the need for targeted educational interventions and public awareness campaigns to enhance the general public's understanding of NAFLD. Providing accurate and up-to-date information about the disease, its consequences, and preventive measures is crucial for improving awareness and knowledge.